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Calorie Calculator

Pick a goal and get your daily calorie target. Six goal levels from losing 1 kg/week to gaining 0.5 kg/week, backed by the Mifflin-St Jeor equation and the standard 7,700 kcal/kg conversion.

Calorie calculator inputs

This calculator is for informational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before making changes to your diet, exercise, or health regimen.

What is a calorie calculator and why does it matter?

A calorie calculator answers one of the most common nutrition questions in the world: "How many calories should I eat per day to reach my goal?" It takes the physics of energy balance — calories in versus calories out — and turns it into a single, actionable daily target. Whether you want to lose fat, hold your weight steady, or add muscle, the first step is knowing the number you are aiming at.

This tool differs from a plain TDEE calculator in one important way: instead of giving you a single maintenance figure and leaving you to do the math, it asks you to pick the exact weight-change rate you want — lose 0.25, 0.5, or 1 kg per week, maintain, or gain 0.25 or 0.5 kg per week — and returns the daily calorie target that produces that result. No guessing, no "what should my deficit be?"

How this calculator works

Under the hood the calculator runs in two stages. First, it estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation (1990), which is the formula most dietitians and researchers use as their default. TDEE equals your Basal Metabolic Rate (BMR) multiplied by an activity factor from the FAO/WHO/UNU tables:

  • Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
  • Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
  • TDEE: BMR × activity multiplier (1.2 sedentary → 1.9 extra active)

Second, the calculator converts your chosen weekly weight-change rate into a daily calorie delta using the standard 7,700 kcal per kilogram figure (Wishnofsky 1958). One kilogram of body fat stores roughly 7,700 kcal, so to lose 1 kg in a week you need a deficit of 7,700 ÷ 7 ≈ 1,100 kcal per day. To lose 0.5 kg/week, the deficit is ≈ 550 kcal/day. The result is your daily target.

A safety floor of 1,200 kcal/day is applied: if your chosen goal would push the target below that, the calculator clamps it. Very-low-calorie diets should only be run under medical supervision, so the tool refuses to produce them.

Worked example

Take a 30-year-old man, 80 kg, 180 cm tall, moderately active (trains three to five days a week), who wants to lose 0.5 kg per week.

  • BMR = (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day
  • TDEE = 1,780 × 1.55 = 2,759 kcal/day (maintenance)
  • Daily deficit for 0.5 kg/week = (0.5 × 7,700) / 7 ≈ −550 kcal/day
  • Target = 2,759 − 550 ≈ 2,209 kcal/day

Eating roughly 2,200 kcal per day, this person should lose about 0.5 kg (1.1 lb) per week. If after two weeks the scale has only dropped 0.3 kg/week, the real TDEE is a bit lower than the estimate and he can shave another 100–150 kcal off his target. If it has dropped 0.8 kg/week he can add 100 kcal back.

How to interpret the result

The number the calculator returns is a starting estimate, not a law of nature. Population equations like Mifflin-St Jeor are accurate to within about ±10% for most healthy adults — which means your real TDEE might be 200 kcal higher or lower than the math predicts. The right way to use the result is:

  1. Eat the target consistently for 10–14 days.
  2. Weigh yourself daily at the same time, under the same conditions.
  3. Take the 7-day rolling average of the weight.
  4. Compare the actual rate of change against your goal.
  5. Adjust the target by 100–200 kcal if needed and repeat.

After one or two adjustment cycles, your real-world maintenance is much better calibrated than any equation could be. Trust the trend line, not a single morning's weight.

Common mistakes

  • Picking too aggressive a goal. A 1 kg/week deficit is a big bite and rarely sustainable for more than a few weeks. Most people do better with 0.25–0.5 kg/week.
  • Overestimating activity level. If you sit at a desk all day and train three times a week, you are moderately active, not very active. The difference is 200–400 kcal.
  • Not tracking food accurately. Self-reported intake is famously underestimated by 20–40%. If the math says you should be losing weight but you are not, start weighing food on a kitchen scale for a week.
  • Chasing the scale day-to-day. Water weight can swing 1–2 kg in 24 hours. Only the weekly average tells you anything.
  • Forgetting to recalculate. As you lose weight your TDEE drops. Rerun the calculator every 2–4 kg of change and update your target.
  • Eating back exercise calories twice. If you picked "moderately active" the exercise is already in your TDEE. Do not add more just because your watch said so.

When to consult a professional

This calculator is a general educational tool and is not a substitute for individualised medical or nutritional advice. Talk to a doctor or registered dietitian before changing your calorie intake if you have diabetes, thyroid disease, cardiovascular disease, kidney disease, a history of eating disorders, are pregnant or breastfeeding, are under 18, are over 65, take medications that affect appetite or metabolism, or need to lose more than 15% of your body weight. For serious fat loss, a qualified professional can also run indirect calorimetry, which measures your BMR directly rather than estimating it, and can tailor the plan to your lab work, training, and lifestyle in a way no calculator can.

Frequently Asked Questions

How many calories should I eat per day?
It depends on your sex, age, weight, height, activity level, and goal. This calculator estimates your maintenance calories (TDEE) with the Mifflin-St Jeor equation and then adjusts that number based on the weight-change rate you pick. For example, a 500 kcal/day deficit produces roughly 0.45 kg (1 lb) of loss per week. Enter your details above to get a personalised number.
Is the 7,700 kcal per kg rule accurate?
It is a useful approximation, not a law of physics. The figure comes from Wishnofsky (1958) and represents the energy stored per kilogram of body fat. Real weight change is messier: water retention, glycogen stores, muscle gain or loss, and metabolic adaptation all skew the short-term picture. Over a month, however, the 7,700 kcal/kg rule lands most people within ±15% of their actual result, which is good enough to plan from.
Why is 1,200 kcal the lower limit?
1,200 kcal/day is a conventional safety floor used by dietitians for adult women, and 1,500 kcal for adult men, because eating below those levels makes it very hard to meet essential vitamin, mineral, and protein needs without supplementation. The calculator caps all targets at 1,200 kcal as a floor. If your goal plus your TDEE would push you below it, you need either a slower rate of loss, more activity, or professional supervision.
Should I lose 1 kg per week or go slower?
Faster is not better. A 1 kg/week loss requires a 1,100 kcal/day deficit, which is sustainable only for people with significant excess weight and good support. For most people a 0.25–0.5 kg/week rate is more realistic: you preserve muscle, feel less hungry, train harder, and are less likely to rebound. The "best" rate is the one you can actually stick with for the entire diet.
How long until I see results?
Scale weight can move within days because of water and glycogen, but visible fat loss takes longer. At 0.5 kg/week, a month of consistent eating produces roughly 2 kg of loss — usually enough to see in the mirror and in how clothes fit. Body composition changes (recomposition) can take 8–12 weeks before they are obvious. Take progress photos every two weeks rather than relying on the scale alone.
What happens if I stop losing weight?
Plateaus are almost always caused by one of three things: (1) your TDEE has dropped because you now weigh less, so your old deficit is no longer a deficit; (2) your tracking has drifted and you are eating more than you think; or (3) water retention from stress, sleep loss, or a new training stimulus is masking real fat loss. Recalculate with your new weight, weigh and log food accurately for a week, and give it 10–14 days before making changes.
Can I eat back my exercise calories?
If you already picked an activity multiplier that includes your training (e.g. "moderately active" for 3–5 workouts per week), your exercise is already in the TDEE number — do not add it again. Adding 500 kcal because your watch said you burned 500 kcal double-counts and will stall weight loss. Only eat back exercise calories if you used "sedentary" as your activity level.
Does this work for gaining weight (bulking)?
Yes. Pick "gain 0.25 kg/week" for a lean bulk or "gain 0.5 kg/week" for a more aggressive bulk. Beyond 0.5 kg/week most of the extra weight is fat, not muscle, because the human body can only build muscle so fast. A 0.25 kg/week surplus of roughly 275 kcal/day is enough for most trainees who have been lifting for more than a year.
Is this safe for teenagers or older adults?
Adolescents under 18 and older adults (65+) have different nutritional needs and should not aggressively restrict calories without medical guidance. The calculator will return a number for ages 13 and up, but we strongly recommend using it only as a rough maintenance estimate for those groups, not as a diet plan. Talk to a doctor or registered dietitian first.
Is this a substitute for medical advice?
No. This calculator is an educational tool that applies standard population equations. It does not account for medical conditions, medications, pregnancy, breastfeeding, eating disorder history, or individual metabolic variation. If you have any of those factors or are planning a major change in weight, talk to a qualified healthcare professional.